Conduritol Beta-epoxide, a saccharide that strongly inhibits beta-glucosidases, was synthesized by a method developed by this section that provides the product in greater yield than previously available and permits the preparation of this compound containing a tracer with extraordinarily high specific radioactivity. Administration of conduritol beta-epoxide to animals produces a syndrome that resembles Gaucher's disease in humans by inhibiting the enzyme glucocerebrosidase. Radioactive conduritol beta-epoxide reacts with the active site of glucocerebrosidase isolated from normal human tissues and from patients with Gaucher's disease. This use of the radioactive conduritol beta-epoxide will materially accelerate the identification of the amino acid substitutions (or deletions) that occur in the glucocerebrosidase molecule in patients with Gaucher's disease.